Governing apparatus



Dec. 11, 1945. SQHWENDNER 2,390J40 GOVERNING APPARATUS Filed May 26,1942 3 sheets sheet 1 INVENTOR HNTHONY E' Scnwszunmm F 16km ATTORNEYWITNESSES:

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B Y I (P? I M ATTORNEY Dec. 11 1945.

GOVERNING APPARATUS Filed May 26, 1.942

3 Sheets-Sheet 3 WITNESSES:

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2' BY I WIV2)/UB\-MM ATTORNEY Patented Dec. 11, 1945 GOVERNING APPARATUSAnthony F. Schwendner, Ridley Park, Pa., as-

signor to Westinghouse Electric Corporation, East Pittsburgh, Pa., acorporation of Pennsyl- Vania Application May 26', 1942, Serial No.444,538

9 Claims, (01. -43) The invention relates. to governing mechanistn foraturbine installation.

Where a turbo-generator operates as a base load machine, it is desirableto provide a. governor having a reasonably wide regulating speed rangeto avoid disturbances in the load carried by the turbine; however, theachievement or this objective may be at the risk of overspeeding, in theevent of full or partial load dump, suflicient- 1y to cause theemergency governor to become.

effective to close the throttle valve. As closure of the throttle valveinvolves again starting the turbine, measures should be taken to preventoperation of the wide speed range governor leading to this result.Therefore, in addition to said governor, which is referred to as theprimary governor, there is provided a, secondary governor having arelatively narrow regulating speed range, the secondary governorbecoming effective when the turbine increases in speed to apredetermined extent above normal and serving to close the admissionvalve at a speed well belowthe speed at which such valve would be closedby the primary governor and safely below that at which the emergencygovernor becomes operative. For example, assuming that the primarygovernor has a regulating speed range of 6 or 8 per cent and that theemergency governor has the usual Accordingly, the invention has for anobject to control the admission of steam to a turbine by means ofprimary and secondary governors constructed and arranged so that theprimary governor normally controls the admission of steam, but, in theevent of full or partial load dump resulting in increase in speed to apredetermined extent, the secondary governor assumes control to preventcontinuance of increase in speed to such an extent as to result inoperation of the emergency governor. 1

Where a'high-pressure turbine driving a generator supplies steam to oneor more low-pressure turbines, each driving its generator, a governor iscustomarily employed to control the ad- 1 mission of steam to thehigh-pressure unit and each turbineis equipped with an auto-stop oremergency governor. With this arrangement, if

' the decline in load is sufliciently rapid, the steam setting torespond to 10 per cent overspeed, if

the secondary governor has a speed regulation of 1 per cent or less andis set to come into operation at 2 per cent above normal speed, it willbe apparent that the second governor will assume control just as soon asthe turbine reaches a speed 2 per cent above normal and that theadmission valve will be closed by that governor when the speed reaches 3per cent above normal. Thus, it will be apparent that, by setting thesecondary governor to govern at a speed just above the normal speedcarried on the system and 'within the regulating speed range of theprimary governor, the latter normally con- 'trols the turbine; however,in the event of partial or sudden load drop, the turbine speed isaccelerated until control of the admission valve is assumed by thesecondary governor, and, as the latter hasa very narrow speed regulatingrange, it is operated to close the admission valve at a speed well belowthe speed at which the emergency governor would become operative.Assuming that control of the turbine has been assumed by the secondarygovernor and it is desired to have control resumed by the primarygovernor, then the speed changer oi the latter is adjusted until thisresult-is achieved. I

in the cross-over connection may accelerate the low-pressure turbineunit or units sufficiently to operate their emergency or auto-stopgovernors.-

Therefore, a further object of the invention is to provide, for eachlow-pressure turbine unit, a

valve in the low-pressur supply line together with a governor for thevalve, the governor being effective at a desired speed above normal andspeed compensated so that it does not interfere with normal control bythe main governor of steam to the high-pressure and low-pressure turblneunits, but, in the event that the speed of the low-pressure unit orunits should reach a predetermined value above normal and below thesetting of the overspeed or emergency governor or governors, thegovernors will be operated, not only to control the valve in thelowpressure supply line, but the main admission valve as well. Moreparticularly; a further object of the invention is to provide, with aninstallation including a high-pressure turbine unit having a cross-overconnection to one or more low-pressure turbine units and having itssteam supply normally controlled by a governor, an intercepting valvefor each low-pressure turbine unit and under control of an additionalgovernor, which is speed compensated for a small percentage ofregulation, for example, 1 per cent, and set to become effective orgovern at a desired percentage, for example, 2 or 3 per cent abovenormal speed, whereby the interceptingvalve or valves may be closed witha rise in speed of 3 or 4 per cent, in spite of the fact that the maingovernor controllingthe supply of steam to the installation-has aregulation of 6 or8 per cent. Thus,

with a speed-compensated additional governor having its speedsetting-suitably adjusted, the' installation may normallyoperate withthe usual regulation and without interference'by the additionalgovernor, while at the same time it is assured that, should the speed ofa low-pressure turbine unit exceed a predetermined amount, the

governor, at IS, the check valve 23 prevents the back fiow of liquidunder pressure through the conduit 22 to the governor, at 2|. n theother hand, should the governor, at 2|, be supplying additional governorcloses both the admission and the intercepting valves. In addition toguarding against operation of an emergency governor because ofacceleration due to steam in the cross-over connection in the event ofsudden load drop, control of the installation by the main governor atthe lower speed may be rapidly resumed I by adjusting the speed changerthereof.

These and other objects are effected by the invention as will beapparent from the following description and claims taken in connectionwith .the accompanying drawings, forming a part of this application, inwhich:

Fig, 1 is a diagrammatic view showing a tur-- bine installation havingthe improvement applied thereto;

Fig. 2 is a detail sectional view showing a modifled form of governor; 2Fig. 3-is a view similar to Fig. '1, but showing a modified form of thecontrolling arrangement; and

Fig. 4 shows a further embodiment of the invention.

so In Fig. 1, there is shown a turbine 9 coupled to the generator l0and'having an admission valve ll operated by servo-motor apparatus, atI2, provided with a pressure-responsive control supplied by the passage4 from the primary governor, at I5, preferably of the hydraulic type andhaving a speed changer Hi. The passage it, isprovided with a check valveI! for the purpose hereinafter referredto. As is customary with the 40.chine, it is desirable that the primary governor, at l5, should have afairly wide regulating speed range, for example, 6 or 8% however, withsuch a wide'range, in the event of full or partial load dump, theturbine may overspeed sufficiently to operate the emergency governor andclose the throttle valve. Therefore, the turbine is equipped with asecondary governor, at 2|, also preferably of the hydraulic type andconnected by a passage 22 to the servo-motor pressure-responsive device,at l3, the passage 22 having a check valve 23 for the purposehereinafter pointed out. The secondary governor, is adjusted foroperation at. a. speed of the turbine inexcess of the normal speed ofthe latter a predetermined smalr extent, for example, 2 or 3per centabove normal, and it has sucha narrow regulating speed range that itrestricts the steam to prevent the attainment of a speed adequate torenderthe emergency governor effective.

With the pressure-responsive device, at l3, be-

ing supplied with liquid under pressure from the liquid under pressureto the pressure-responsive device, the check valve prevents back fiow tothe governor, at l5.

The governor apparatus, at 2|; is comprised by v transformer apparatus,at 24, providing fluid un-- derpressure for the passage 22 and thepressure-responsive device, at |3,'of the admission valve servo-motor,the transformer being provided with means, hereinafter described, towhich force dependent upon turbine speed may be apdevice, atl3, to whichfluid under pressure is accumulator or airbell.

pensation would not raise the speed too close.

' ?Where the turbine is used as a base load ma plied to control thepressure.

The pressure transformer, at 24, includes structure providing a space,at 25, which communicates with the passage 22, fluid under pressurebeing supplied to the space, at 25. by an orifice 26 communicating withany source of suitably high pressure. Fluid pressure in the space, at25, is controlled by means of an escape port 21 with which cooperates'avalve 28 associated with an operating member 29 to which force depend- 5cut upon turbine speed is applied.

Preferably, the valve 28' is of the cup type and it presents an areasubject to fluid pressure existing in the space 25. The cup valve isformed to provide an additional pressure area 33 equal to and in opposedrelation with respect to the area provided by the cup valve 28. Thepiston area 31) is exposed to pressure in the chamber 3|. With absenceof fluid pressure in the chamber 3|, the governor would have the usualregulation, that is, there would be a percentage of speed change from noload to full load to make operation possible. If pressure is provided inthe chamber 3|, the effect thereof is to reduce the speed change due toload change, and the more this pressure is increased the greater theextent of speed correction until, with equality of pressures in thespace 25 and in the chamber 3|, the isochronous condition is reached.

To provide stability, the arrangement should be such that change inpressure in chamber 3| lags 'a desired slight amount with respect tochange in the space 25. This result is conveniently achieved'by the useof an orifice and an to the emergency trippingspeed, it is preferablyemployed. Therefore, there is shown means for controlling pressure inthe chamber 3|. A first passage 32 communicates with the space, at 25,

a second passage 33 communicates with the pressure chamber 3|, and thereis provided ,a drain space 32. A viscous orifice, at 35, for example,

is arranged between the first and second passages 32and 3,3, and asecond viscous orifice, at 36, is arranged 'betweenthe second passage 33and the drain space 34. It is characteristic of a viscous orifice thatthe pressure drop or resistance varies with the length and the flowvaries directly as the pressure drop and not as the square rootthereof,-that is, it has a linear relation as between flow and pressuredrop.

Hence, adjustment in length results in a propor-',

tionate adjustment in pressure drop or pressure. As shown, the first andsecond'viscous orifices. at 35 and 36, are adjustable to vary thelengths thereof,-the' first orifice, at 35, being shortened to increasethe pressure .in the chamber 3| and the second orifice, at 36, beinglengthened and vice versa, the length of the first orifice being,

varied to vary the pressure in the chamber 3| with If partial speedcom-2 preservation of the same total orifice length of the first andsecond orifices between the first passage 32 and the drain passage 34.The advantage of the arrangement illustrated ,is that changes inviscosity do not affect the pressure provided inthe chamber 3|, for thereason that any change in viscosity afiects the orifices equally.

The viscous orifice arrangement is more particularly described andclaimed in the applica- .tion of O. N. Bryant, Serial No. 443,777, filedMay 20, 1942 (now Patent No. 2,323,115, dated June 29,1943) and assignedto the assignee of the present application. Each orifice embodies innerand outer members, one orboth of which are threaded to provide a helicalviscous flow passageand the members being shortened to vary the lengthoithe flow passage. As shown, the visspring 49a connected to the speedadjusting device 5|a.

In Fig. 3, there is shown an arrangement which is similar to Fig. 1,exceptthat the turbine is equipped with an induction line 53 for supp yng steam to a suitable intermediate stage. A valve 54 is arranged in theline 53 and it is controlled by means of a servo-motor, at 55, having apres-' cous orifices, at 35 and at 36, embody outer membus 31 and 38with which cooperate inner members 39 and 40, the inner .memberspreferably being unitary, as illustrated. Either or both of the innerand outer members or the orifices may be threaded to provide helicalviscous flow passages. The unitary inner merribers 39 and 40 areadjustable axially to vary the lengths of the orificepassages, onepassage being shortened while'the other is lengthened, and vice versa,in

sure-responsive control device 56. Liquid under .controlling pressure issupplied from either the primary governor, at l5, or the, secondarygovernor, at 2|, by means of the conduit 51, the latter being connectedto the conduit 22 of the governor, at 2|, and being connected by thepassage 58, the pressure-responsive device l3, and the r thereby, thecheck valve operating to prevent order that the length-of the passageofthe orifice,

at 95. be varied while maintaining the length of passages of bothorifices, at 35 and 36, between the passage 32 and the drain space 34constant. Any suitable means 43 may be provided for adjusting the innermembers of the viscous orifices.

The operating member 29 may have force applied thereto in any suitablemanner. As shown, an impeller 45 driven by the turbine provides, liquidwhose'pressure varies substantially as the square of the turbine speedand the-liquid is supplied to the chamber 46 formed in part by theabutment 41 and the bellows 48 connected thereto. The abutment 4'lengages the lower end of the operating member 29 and it has a pressurearea or face 49 exposed to pressure in the chamber 46. The force ofliquid pressure applied to the abutment 41 is opposed by that of theload spring 50 whose face may'be varied by the adjusting apparatus 5|.

By adjusting the apparatus 5|, the force of the load spring 50 may bealtered to alter the governing speed. By this means, the secondarygovernor may be set to governat a speed 2 or 3 per cent above normal.But for the feature of speed compensation for load change, thisoverspeed adjustment coupled with the normal regulation, which wouldthen be inherent in the secondary governor, might mean oversp'eeding tothe point where the emergency governor would be rendered effective.Therefore, instead of the secondary governor having the usualregulation, its

regulation is reduced to l per cent or less by any back flow of liquidto the governor, at l5.

In Fig. 4, there is shown an embodiment of the invention applied to across-compound turbine installation comprising the high-pressure turbine911 Joined by the cross-over connection '59 to one or more low-pressureturbines 9b. The turbines 9a and 9b drive generators Illa and lllbconnected in parallel to an electrical system in the customary manner.

The high-pressure turbine ila has an admission.

valve I la controlled by the primary governor, at l5a; however, insteadof the secondary governor,

at 2|a, being operated by the same turbine, as in Fig. 1, it is operatedby the low-pressure turbine 9b. Also, the low-pressure turbine hasanemergency governor, at 2011, responsive to overspeeding to bring aboutclosing of the throttle valve means of the speed compensator. Thus,while the secondary governor, ait 2|, is set by means of the speedadjusting device 5| to start closing the admission valve at 2 or 3 percent overspeed,

' whereby interference with normal control by-the primary governor, atI5, is avoided, yet, in the event of sudden load drop and consequentovers'peeding, the secondary governor'co nes into play at the setoverspeed to start closing the admission valve and the latter iscompletely closed with a very. small speed change due to load changebecause of the speed compensator.

In Fig. 2, instead of the speed-responsive force being provided by fluidpressure, it is provided by The operations already described inconnection I with Fig. 1 also occur in the embodiment of Fig. 4;

and, in. addition, in case the entrapped steam in the cross-overconnection is sufilcient to accelerate the low-pressure turbine, in theevent of partial or full load dump, intercepting valves 6|! controlcommunication of the cross-over connection with the low-pressureturbines and prevent such acceleration of the latter.

The intercepting valves 60 are opened and closed by servo-motors, at 6|,each having a pressure-responsive control device, at 62, and thepressure-responsive control devices are supplied with liquid underpressure by means of the conduit 51b of the secondary governor, at 2la,the latter governor also having a conduit passage 58b communicating withthe pressure-responsive device of the servo-motor, at |2a. A check valvellb normally interrupts the conduit 581) when the primary governor, atl5a, is effective, but, when the secondary governor, at 2 la, becomeseffective,

it allows for the transmission of fluidunder pressure from the latter tothe pressure-responsive device, at l3a, of the servo-motor, at l2a.

As the primary governor, at l5a, has a fairly wide regulating speedrange, for example, of the order of 6 or 8 per cent, and as apparatus ofthis character may accelerate with a high degree of rapidity whenpartial'or full load dump occurs,

it is necessary to resort to other means of control,

otherwise the primary governor may not act quick enough to prevent theattainment 01a speed suflicient to render the emergency governor effec-Therefore, as in Fig. 1, a secondary governor is is used, and it is setto become efiective at a speed higher to a predetermined extent than thenormal speed but well below the overspeed at which the emergencygovernor becomes efiective. For example, as in Fig. 1, the secondarygovernor may be set to become effective at 2 or 3 per cent above thenormal speed. v

As the secondary governor is speed compensated, it may have a desirablynarrow regulating speed range, for example, lper cent or less. As-

.suming that the secondary governor is set to become effective at 2 percent overspeed, then, when the speed reaches 3 per cent, the valves willbe completely closed, the secondary governor, at Ma, bringing aboutclosing of the intercepting valves 60, as well as closing of theadmission valve Ila. As the generators Illa and lb of-the highand-low-pressure turbines are connected together electrically, it willbe apparent that the primary and secondary governors are capable ofoperating to control the valves I I a and. 60 in the same manner as theywould be controlled if the secondary governor, at Ma, were operated bythe high-pressure turbine 9a; however, othe reasons, for example,interruption of the electrical connection between the high andlow-pressure turbines, make it desirable to have the secondary governoroperated from a low-pressure turbine;

' Regardless of what may happen, as soon as the low-pressure turbineoverspeeds 2 per cent, the intercepting valves close and pressuresupplied v through the line 58b acts on the servo-motor, at

We, to bring about movement of the valve l la in a closing direction torestrict the sup ply of steam so as to avoid overspeeding to an extentsumcient to trip the. emergency governor and close the throttle valve.In addition to movement of the admission valve- Ila in a closingdirection tending to restrict acceleration of the high-pressure turbine,the building up of back pressure in the cross-over connection 59 whenthe interceptingvalves 60 are closed also tends to achieve the samepurpose for the reason that the pressure drop across the high-pressureturbine is thereby reduced.- To limit the attainable pressure in thecross-over connection, the latter is preferably provided with a-reliefvalve 63 set to open at a predetermined pressure. The termturbine'installation, as used herein, has the significance of one ormore turbine units having a single passage ase vao but below saidpredetermined overspe'ed, and

speed-compensating means for the secondary gov--v ernor providing forsuch; a narrow regulating speed range thereof that it is efiective tooperate the governor valve to restrict the flow of elastic fluidsufllciently to prevent the attainment-oi said predetermined overspeedby the turbine installation.

2. The combination as claimed in claim 1 wherein the speed-compensatingmeans includes means providing for narrowing of the speed-regulatingrange of the secondary governor to a desired extent. Y

3. The combination as claimed in claim 1 wherein the speed-changingmeans includes a speed changer for the primary governor providing foradjustment of the latter to increase its goveming speed setting incidentto regaining control of the turbine installation from the secondarygovernor.

4. In a turbine installation having a throttle valve plosed in responseto a predetermined speed, a governor valve; pressure-responsive meansfor controlling the governor valve; a primary governor responsive tospeed of the turbine installationv nd providing fluid under controllingpressure; a

secondary governor responsive to speed of the turbine installation andproviding fluid under controlling pressure; said secondary governorincluding means for adjusting its speed setting and means forcompensating to a substantial extent for speed change \thereof due toload change;

conduits for supplying fluid under controlling pressures from thegovernors to the pressure responsive means; andcheck valves. in the condduits for isolating the primary governor from fluid under controllingpressure supplied by the secondary governor and vice versa.

5. In a turbine installation having. a throttle valve closed in responseto a predetermined overspeed, a governor valve, an induction passage forsupplying steam to an intermediate stage of the turbine installation, aninduction mary and secondary governors for alternatively controlling"both the governor and induction valves, the primary. governor having awide regulating speed range and the secondary governor having a narrowregulating speed range, and means for setting the secondary governor sothat it is normally ineiiective but becomes eflective upon increase inturbine installation speed to an through which the flow of steam iscontrolled by the governors in the manner described.

While the invention has been shown in several forms, it Will be obviousto those skilled in the art that it is not so limited, but issusceptible of various other changes and modifications without departingfrom the spirit thereof, and it is desired, therefore, that 1y suchlimitations shall be'placed thereupon g are specifically set forth intheap ended claims What 1 claimed is: e

1. In a turbine installation having a throttle valve closed in responseto a predetermined overspeed, a governor valve/a primary governorresponsive to turbine installation speed and having such a wideregulating speed range that the turbine installation may attain'saidpredetermined -overspeed, a secondary govepnor responsive to turbineinstallation speed, speed-changing means providing for relativeadjustment of the governgrs such that the secondary governor has itsregulating speed range within that of the primary governor but beginning at a speed above normal extent such that it is assured that thegovernor and induction valves-shall-restrict the flow of steam to theturbine installation sufficiently to prevent the attainment of anoverspeed adequate to bring about closing of the throttle valve.

6. In a' turbine installation having 'a throttle valve closed inresponse to a predetermined over-' speed, a governor valve; an inductionpassage for supplying steam to an intermediate stage of the 7 comeseffective upon increase in turbine installa tion speed to anextentsuch-that it is assured that the governor and induction valves shallrestrict sufficiently the flow of steam to the turbine installation toprevent the attainment of an overvalve for controlling flow through theinduction passage, pri- 1 speed adequate to bring about closing or thethrottle valve.

7. In a turbine installation having a throttle valve closed in responseto a predetermined overspeed, a governor valve; an induction passage forsupplying steam to an intermediate stage of the turbine installation; aninduction valve for controlling the flow of steam through the inductionpassage; primary and secondary governors operated by the turbineinstallation; and means actuated by each governor for controlling boththe governor and induction valves; said secondary governor includingmeans for adjusting its speed 'setting, means for reducing the speedchange thereof due to load change, and means for adjusting thelast-named means. l

8. In a turbine installation having a throttle valve closed in responseto a predetermined overspeed and including a high-pressure turbinejoined by cross-over connection to a low-pressures turbine, an admissionvalve for the highpressure turbine, an intercepting valve for thecross-over connection and located adjacent to the low-pressure turbine,a primary governor oper ated by the high-pressure turbine, a secondarygovernor operated by the low-pressure turbine, said primary governorhaving a wide regulating speed range and said-secondary governor havinga narrow regulating speed range, means actuated by the primary governorto control the admission valve, means actuated by the secondary governorto control both the admission and intercepting valves, and means forsetting the secondary governor so that it is normally ineffective butbecomes efiective upon increase in speed to an extent such that it isassured that the valves shall restrict the supply of steam to theturbines sumciently to prevent the attainment of an overspeed adequateto bring about closing of the throttle valve.

9. The combination with a turbine installation including a high-pressureunit for supplying motive fluid-through a, cross-over connection to oneor more low-pressure units, of a primary governor normally controllingthe supply of motive fluid to the installation; a valve in thecross-over connection for each low-pressure turbine unit and locatedadjacent to the latter; and a secondary governor responsive tolow-pressure turbine unit speed and operatively connected to the valveor valves; said secondary governor including means for adjusting itsspeed, means for effecting reduction in speed change due to load change,and means for adjusting the last-named means.

ONY F. SCHWENDNER.

